Downloaded from https://www.everyspec.com ADS-79D-HDBK damage assessment estimates for specific aircraft components will require data management infrastructure that can relate aircraft regime recognition and flight history data to individual components and items which are tracked by serial number. Knowledge of the actual aircraft usage can be used to refine the baseline ―worst case‖ usage spectrum used to determine the aircraft service schedules and component retirement times. The refinement of the ―worst case‖ usage spectrum, depending on actual usage, could result in improved safety and reduced cost, or improved safety or reduced cost.
The criteria for acceptance of airworthiness credits from a fatigue life management perspective are provided in Appendix A. The refined usage spectrum enables refining fleet component retirement intervals to account for global changes in usage of the aircraft. The usage spectrum may be refined for specific periods of operation. An example is refining the usage spectrum to account for the operation of a segment of the fleet in countries where the mean altitude, temperature, or exposure to hazards can be characterized. The use of DSC data to establish an updated baseline usage spectrum is the preferred method (compared with pilot survey method).
The individual component fatigue damage assessment is dependent on specific systems to track usage by part serial numbers. In this case, the logistics system should be capable of tracking the specific part (by serial number) and the specific aircraft (by tail number). The actual usage of the part, and its Remaining Useful Life, can be determined from the usage data of the aircraft (tail numbers) for the part (serial numbers).
Because usage monitoring and component part tracking are not flight critical systems, if either of these systems fail, the alternative is to apply the most current design usage spectrum and the associated fatigue methodology for any period of flight time in which the usage monitor data or the part tracking data is not available. As such, use of the individual component fatigue damage assessment method does not eliminate the need to periodically refine the fleet usage spectrum based on use of DSC data. Specifics for the implementation of the individual component fatigue damage assessment are given in Appendix B:
Regime Recognition/Flight State Classification with Validation of Regime Recognition Algorithms, and Appendix A: Fatigue Life Management. 4.2.4 Remediation of fatigue sensitive components. Remediation may be used to address components that are found to be routinely removed from service without reaching the fatigue safe life (a.k.a. component retirement time, CRT). The process of remediation involves the identification of removal causes that most frequently occur. Often the cause of early removal is damage such as nicks, dings, scratches, or wear. Details for implementation of remediation are found in Appendix A.
When remediation action is taken to increase repair limits, it should be documented in maintenance manuals, including Technical Manuals (TMs) and Depot Maintenance Work Requirements (DMWRs). 4.2.5 Ground based equipment and information technology. The use of data to modify maintenance practice is the heart of CBM. As such, the ground based equipment that is used to complete the data processing, analysis of sensor data, infer components integrity, forecast remaining useful life, and decide appropriate maintenance actions, is a vital part of the CBM system.
The CBM data architecture and ground based equipment used to interface with the data should be capable of supporting several types of management actions that support optimal maintenance scheduling and execution: a. Granting CBM credits or debits (changes to scheduled maintenance) based on usage/loads monitoring and damage accrual or CI/HI values requires accurate configuration management of components and parts installed on the aircraft. 18